The present embodiments relate generally to articles of footwear that may be used for athletic or recreational activities such as running, jogging, training, hiking, walking, volleyball, handball, tennis, lacrosse, basketball and other similar activities.
Articles of footwear can generally be described as having two primary elements, an upper for enclosing the wearer's foot, and a sole structure attached to the upper. The upper generally extends over the toe and instep areas of the foot, along the medial and lateral sides of the foot, and around the back of the heel. The upper generally includes an ankle opening to allow a wearer to insert the wearer's foot into the article of footwear. The upper may incorporate a fastening system, such as a lacing system, a hook-and-loop system, or other system for fastening the upper over a wearer's foot. The upper may also include a tongue that extends under the fastening system to enhance adjustability of the upper and increase the comfort of the footwear.
The sole structure is attached to a lower portion of the upper and is positioned between the upper and the ground. Generally, the sole structure may include an insole, a midsole, and an outsole. The insole is in close contact with the wearer's foot or sock, and provides a comfortable feel to the sole of the wearer's foot. The midsole generally attenuates impact or other stresses due to ground forces as the wearer is walking, running, jumping, or engaging in other activities. The midsole may be formed of a polymer foam material, such as a polyurethane (PU), a thermoplastic polyurethane (TPU), or ethylvinylacetate (EVA), that attenuates ground impact forces. In some cases, the midsole may incorporate sealed and fluid-filled bladders that further attenuate and distribute ground impact forces. The outsole may be made of a durable and wear resistant material, and it may carry a tread pattern to provide traction against the ground or playing surface. For some activities, the outsole may also use cleats, spikes, or other protrusions to engage the ground or playing surface and, thus, provide additional traction.